The present invention relates to a method for real-time scheduling of processes at distributed manufacturing sites.
Industrial automation has increased in scope and refinement with time. In general, industrial automation has focused on continuous processes comprising a plurality of distributed and interacting manufacturing sites. This covers in particular a broad range of manufacturing execution systems allowing an integrated workflow which are offered by the Siemens Corp. under its SIMATIC® product family. The virtue of this manufacturing design is that it provides adaptability to a varying product mix. The drawback is the resulting complexity of processes, management and quality control.
Automatic manufacturing proves to be a data-and-information-rich structure with an elevated number of parameters may be required to merely describe the manufacturing. Efficient scheduling is thus imperative.
Scheduling is the process that allocates resources for manufacturing. Often, the schedule is a result of simple local scheduling policies that are evaluated at run-time (e.g. shortest job first, longest job first, first in first out).
EP 0 679 972 A1 discloses a systematic scheduler for manufacturing lots of items by process resources. To determine which lot to schedule next for a process resource, an evaluation is made from a set of selected lots and a set of selected process resources. Scores are assigned to each pairing of a lot and process resource. The pair with the best score determines which lot will be processed on which process resource.